The present invention relates to a connectable drive for a screwdriver spindle.
Such drives are used in screwdrivers in which a maximum transferable limit torque is stipulated at which a claw clutch is disengaged. An over-detent clutch sees to it that claws and mating claws of the claw clutch are brought completely out of engagement as soon as a prearranged limit torque has been exceeded so that troublesome noise of an over-ratcheting claw clutch is avoided.
One drive of this type is known from Federal Republic of Germany OS 1,678,656. In that reference, a driver sleeve of a claw clutch is part of an over-detent clutch which consists of oblique claws on the driver sleeve and rollers which correspond thereto upon moving thereover by the oblique claws, the driver sleeve is displaced in axial direction, carrying along a mating part of the claw clutch. A disengageable safety consists in connection of radially displaceable balls which can be moved into an inner circumferential groove of a gear wheel and are controlled by a spring-loaded mandrel which is arranged for axial displacement in a work spindle which is developed as a hollow shaft. The drive spindle is provided with radial passage holes for passage of the balls and the axially displaceable control mandrel is provided, on its front, with a conically tapering displacement surface in order to be able to exert a radial force on the balls. The parts of said drive are difficult to manufacture and complicated to assemble and they must, if only for this reason, be fitted carefully to each other so that jamming of the disengageable safety of the clawclutch part is avoided.